Activated human Hageman Factor (HFa) participates in a series of reactions including those associated with activation of the intrinsic blood coagulation cascade, the kinin-generating system, and the plasma fibrinolytic system. Hageman Factor is activated during its proteolytic cleavage by plasma kallikrein, yielding a functionally active fragment (HFf) with a molecular weight of 28,000. HFf is, itself, a potent activator of prekallikrein. Thus, once HF is activated, there is a reciprocal activation of prekallikrein to kallikrein, and Hageman Factor to HFa (or HFf). The mechanism by which the above sequence is initiated is unknown. That is, what molecules provide the initial triggering proteolytic activity for the HF-HFa-prekallikrein-kallikrein-HF cycle? We have recently observed that supernatants from passively sensitized antigen challenged human lung were capable of generating kinins by directly activating all three proteins in the Hageman Factor dependent kinin-generating pathway. Three proteins from the supernatant were partially purified over SP-Sephadex, DEAE-Sephacel, and Sepharose 6B columns. Like plasma kallikrein, the lowest molecular weight protease (approximately 70,000) cleaves zymogen HF into fragments of 52,000 and 28,000 M.W. and also cleaves human plasma kininogen, thus generating biologically active kinin. The other two proteins are both arginine esterases, one generates a kinin from low molecular weight kininogen, while the other activates prekallikrein. Our objectives are to complete the purification of these three proteins which are derived from human lung by IgE-mediated mechanisms. We will also complete the purification of a basophil protease with kallikrein-like activity. (BK-A). These proteases will be purified by ion exchange, gel filtration, and affinity chromatography. If necessary, preparative isoelectric focusing will also be utilized. Our data suggest that these proteases may link IgE-mediated reactions with inflammatory processes of the Hageman Factor dependent kinin-generating, coagulation, and fibrinolytic pathways. A major objective of this proposal will be to attempt to assess the contribution of these proteases to the pathogenesis of inflammatory disorders of the human lung.